This invention relates to network communications couplers and more particularly to a coupler that performs its functionality in software.
A coupler is a communications device that maps data structures and operational behaviors between two dissimilar communication environments. In other words, a communications coupler interconnects a first network that uses a first protocol to a second network that uses a second protocol.
The basic structure of a typical communication coupler is well known to those of ordinary skill in the art and is shown in FIG. 1. Coupler 10 interconnects a first network 12 with a second network 14 and includes three software implemented functions in performing that interconnection. Two of these functions are a first communication protocol stack 16 and a second communication protocol stack 18. Stacks 16 and 18 provide the interface of the coupler 10 with the first and second networks 12 and 14, respectively.
The coupler 10 further includes a mapping program 20 that maps the protocols of the first and second networks 12 and 14 to each other. While not shown in FIG. 1, it is well known to those in the art that coupler 10 has to run on a suitable hardware platform and include suitably arranged circuit boards to connect the first protocol stack 16 to the first network 12 and the second protocol stack 18 to the second network 14.
One embodiment of a prior art communications coupler is the coupler sold by the assignee of the present invention that is used to interconnect the assignee""s distributed process control systems (DCS) to the Ethernet.
That coupler has a multiplicity of components including a personal computer that runs a server program, hardware to interface with the communications network in the DCS, a network interface circuit, termination units, and a database engine for buffering for data and control information. This coupler while providing a very good interconnection between the DCS and the Ethernet does have a large footprint, consumes a fair amount of electrical power, requires multiple input power and cannot be adjacent to the process controlled by the DCS as the coupler is sensitive to environmental conditions.
In contrast thereto, the coupler of the present invention is an integrated solution that has a smaller footprint, uses less electrical power, has a single input power requirement, has a higher capacity and can be located adjacent to the process controlled by the DCS. Further the coupler of the present invention can be accessed externally using standard network protocol for maintenance purposes and allows for remote analysis of its performance.
The present invention is also a method for use with those of a plurality of commands sent by at least one client on a network connected to a network communications coupler designated by the at least one client as delayed response commands. The method comprises:
designating by the at least one client by means of a predetermined key value provided by said at least one client which of the commands are delayed response commands, said at least one client using said predetermined key value to retrieve a reply to said at least one delayed response command executed by said coupler;
storing in the coupler a first instance of a template, where the first instance is used to store in the coupler at least one of the delayed response commands during execution of the at least one delayed response command by the coupler; and
storing in the coupler a second instance of said template, where the second instance is used to store in the coupler a reply to the at least one delayed response command executed by the coupler until the reply is retrieved by the client.
The present invention is also a system that comprises:
a first network having at least one client connected thereto;
a second network;
the first and second networks having different protocols;
a network communications coupler connected to both the first network and the second network;
the at least one client sending a plurality of commands to the coupler and designating at least one of the commands as a delayed response command;
the coupler for storing one or more instances of a command interpreter, the command interpreter providing a command/reply interface for data and command exchange between one of the at least one clients and the second network and the coupler also for storing a first instance of a template, the template associated with one or more instances of the command interpreter, the first instance used to store in the coupler at least one of the delayed response commands during execution of the at least one delayed response command by the coupler; and for storing a second instance of the template, the second instance used to store in the coupler a reply to the at least one delayed response command executed by the coupler until the reply is retrieved by the client.
The invention is further a system that comprises:
a first network having at least one client connected thereto;
a distributed control system comprising a second network;
the first and second networks having different protocols;
a network communications coupler connected to both the first network and the second network;
the at least one client sending a plurality of commands to the coupler and designating by means of a predetermined key value provided by the at least one client at least one of the plurality of commands as a delayed response command, the at least one client using the predetermined key value to retrieve a reply to the at least one delayed response command executed by the coupler;
the coupler for storing one or more instances of a command interpreter, the command interpreter providing a command/reply interface for data and command exchange between one of the at least one clients and the second network and the coupler also for storing a first instance of a template, the template associated with one or more instances of the command interpreter, the first instance used to store in the coupler at least one of the delayed response commands during execution of the at least one delayed response command by the coupler; and for storing a second instance of the template, the second instance used to store in the coupler a reply to the at least one delayed response command executed by the coupler until the reply is retrieved by the client.
The present invention is a method for use with those of a plurality of commands sent by at least one client on a network connected to a network communications coupler designated by the at least one client as delayed response commands. The method comprises:
storing in the coupler one or more instances of a command interpreter, the command interpreter providing a command/reply interface for data and command exchange between one of the at least one clients and a control network connected to the coupler;
storing in the coupler a first instance of a template, the template associated with one of the one or more stored instances of the command interpreter, the first instance used to store in the coupler at least one of the delayed response commands during execution of the at least one delayed response command by the coupler; and
storing in the coupler a second instance of the template, the second instance used to store in the coupler a reply to the at least one delayed response command executed by the coupler until the reply is retrieved by the client.